The present invention relates generally to communication networks, and more specifically, to a method and system for uniformly handling IP (Internet Protocol) and MPLS (MultiProtocol Label Switching) path calculations to maximize hardware path resource utilization.
The rapid growth of the Internet and the widespread deployment of networks built around the Internet Protocol suite are creating a demand for new capabilities in IP networks. MPLS provides a number of powerful capabilities such as traffic engineering, etc. As with IP routers, MPLS nodes use a routing protocol such as OSPF or IS-IS to calculate network paths and establish reachability. Multiprotocol Label Switching is an IETF initiative that integrates Layer 2 information about network links (bandwidth, latency, utilization) into Layer 3 (TP) in order to simplify and improve IP packet exchange. MPLS provides network operators a great deal of flexibility to divert and route traffic around link failures, congestion, and bottlenecks. MPLS based networks are becoming increasingly important for today's backbone Internet.
In MPLS, data transmission occurs on label-switched paths (LSPs). LSPs are a sequence of labels at each and every node along the path from the source to the destination. LSPs are established prior to data transmission (control-driven). The labels, which are underlying protocol-specific identifiers, are distributed using label distribution protocol (LDP) or RSVP or piggybacked on routing protocols like multiprotocol border gateway protocol (MPBGP). Each data packet encapsulates and carries the labels during their journey from source to destination. High-speed switching of data is possible because the fixed-length labels are inserted at the very beginning of the packet or cell and can be used by hardware to switch packets quickly between links.
When packets enter an MPLS-based network, Label Edge Routers (LERs) give them a label (identifier). These labels can contain information based on the routing table entry (i.e., destination, bandwidth, delay, and other metrics). Once this classification is complete and mapped, different packets are assigned to corresponding Labeled Switch Paths (LSPs), where Label Switch Routers (LSRs) place outgoing labels on the packets. With these LSPs, network operators can divert and route traffic based on data-stream type and Internet-access customer.
With MPLS, incoming packets (predominantly IP packets) are assigned with a label when the packets enter the MPLS network. Packet forwarding is done based on label information within the MPLS core network. In order to maximize network performance and get path protection, it is a common practice to create multiple paths within a network that the packets can take to reach their final destinations. This is referred to as traffic load sharing among multiple paths. When an MPLS enabled network is part of a bigger network, it is possible that incoming IP packets can take both MPLS and IP paths to their destinations, depending on particular traffic flow information contained in the packets.
In today's routers, packets are typically forwarded with the assistance of ASIC hardware. After an IP packet enters a router, the router decides the next hop or path the packet needs to go by looking up the routing table, typically using the destination address of the IP packet. When load sharing paths are available, multiple hardware paths need to be set up for a given route. The conventional approach to deal with a group of mixed IP and MPLS paths is to deal with them separately. Since IP paths are based on the next hop IP address and MPLS paths are based on the MPLS encapsulation string, this appears to be the natural thing to do as each path has its unique characteristics (IP address and label stack). If the paths contain both IP and MPLS path, the hardware paths must contain different information in order to forward the packets onto MPLS or IP paths. Thus, with this approach, each route requires independent hardware path resources to support IP and MPLS mixed load sharing paths.
Due to ASIC resource limitations, it is often required that paths that belong to the same load sharing group must be allocated in contiguous blocks. Each MPLS path uses a different label stack, so each MPLS path requires a separate hardware path. However, there are only a finite number of hardware path resources available on a router system.
There is, therefore, a need for a method and system that treats IP and MPLS paths in a uniform way when organizing, sorting, and comparing IP and MPLS paths in order to achieve maximum hardware path resource utilization.